In a potentiometer of one metre length, an unknown emf voltage source is balanced at `60 cm` length of potentiometer wire, while a `3` volt battery is balanced at `45 cm` length. The the emf of the unknown voltage source is.

Options

A. 3V
B. 2.25V
C. 4 V
D. 4.5 V

Answer

C

Explanation

`E_(1)/E_(2)= I_(1)/I_(2) rArr E/3 = 60/45 rArr E = (60 xx 3)/45 = 4` volt